This book presents the first sustained analysis of the reception of the Aristotelian golden mean and related ideas of moderation in the literature and thought of early modern Spain (1500-1700). It explores the Golden-Age understanding of Aristotle's doctrine as a prolegomenon to literary study, and its allegorical reformulation in the myths of Icarus and Phaethon, before arguing that scrutiny of how the mean and the related concept of ethical moderation are treated by early modern authors represents a vital but underexploited tool for literary analysis. Particular attention is paid to detailed case studies of works by three canonical authors--Garcilaso, Calderón, Gracián--demonstrating the value of the mean as a locus of critical attention, as analysis of its presentation allows several long-standing disputes in the scholarship on these authors to be newly resolved.